Fan motor

ABSTRACT

Fan motor  1  has: a stator  6,  a rotor  4  having a rotary shaft  22,  a cover portion  8  and bracket  2  surrounding the entirety of the stator  6  and rotor  4  in a liquid-tight manner except for the top end portion of rotary shaft  22,  and a fan member  10  affixed to the top end portion of the rotary shaft  22;  on cover portion  8  and bracket  2,  an insertion hole  42  projecting outward of cover portion  8  and bracket  2  is formed on cover portion  8  and bracket  2,  penetrating the top end portion of rotary shaft  22,  and a cover portion bearing  44  is erected between insertion hole  42  and rotary shaft  22.

TECHNICAL FIELD

The present invention pertains to a fan motor, and more particularly to a fan motor with an outer rotor structure in which the stator is positioned on the outer side of the rotor.

BACKGROUND ART

In order to prevent the intrusion of surrounding dust, liquid droplets, and the like into the interior, the use of a water resistant structure has been known in conventional motors, as disclosed for example in Patent Citation 1. The fan motor disclosed in Patent Citation 1, as depicted in FIG. 2, comprises a rotor 102 with a rotary shaft 100, a stator 104 disposed on the inner side of rotor 102, and a surround body 106 surrounding the entirety of rotor 102 and stator 104. The top end of rotary shaft 100 penetrates insertion hole 108 formed on surround body 106 and projects on the outside of surround body 106; fan member 110 is affixed to the top end portion thereof. In a fan motor of such a structure, in order to prevent water intrusion from the gap 112 between the insertion hole 108 on surround body 106 and rotary shaft 100, passage 114, which communicates with gap 112, is formed in a maze shape by erecting an irregular surface on items such as surround body 106 and fan member 110.

PRIOR ART REFERENCES Patent Citations

Patent Citation 1: Patent No. 4822021

SUMMARY OF THE INVENTION Problems the Invention Seeks to Resolve

However, in such conventional fan motor 100 structures, it is difficult to declare this a perfect waterproofing and dust proofing structure, notwithstanding the formation of passage 114 into a maze shape, due to the existence of gap 112.

The present invention therefore has the object of providing a fan motor capable of achieving reliable waterproofness and dustproofness.

Means for Resolving the Problem

In order to achieve the aforementioned object, the fan motor of the present invention has: a stator, a rotor having a rotary shaft, a surround body surrounding the entirety of the stator and rotor in a liquid-tight manner except for the top end portion of the rotary shaft, and a fan member affixed to the top end portion of the rotary shaft; an insertion hole is formed on the surround body in order to insert the top end portion of the rotary shaft and cause it to project on the outside of the surround body, and a surround body-side bearing is provided between the insertion hole and the rotary shaft.

In the present invention thus constituted, a surround body shaft is provided between the insertion hole and the rotary shaft, therefore the gap between the surround body and the rotary shaft is plugged by the surround body bearing. Since the surround body can surround the rotor and the stator in a liquid-tight manner by utilizing the bearing that supports the rotary shaft, reliable waterproofness and dustproofness of the fan motor can be accomplished.

In the present invention the rotor is preferably disposed outside the stator, the stator-side bearing is placed between the stator and the rotor, and the rotor is affixed to the rotary shaft between the surround body bearing and the stator-side bearing.

In the present invention thus constituted, an “outer rotor” structure is adopted whereby the rotor is disposed outside the stator, and the rotor is affixed to the rotary shaft between the surround body-side bearing and the stator-side bearing, therefore the rotor is supported by a double-holding structure comprising the surround body-side bearing and the stator-side bearing. As a result, rotary operation of the rotor is stable, and a stable rotary motion by the fan motor is obtained.

BRIEF DESCRIPTION OF FIGURES

FIG. 1. A cross section of a fan motor according to an embodiment of the present invention.

FIG. 2. A cross section of a conventional fan motor.

EMBODIMENT OF THE INVENTION

Below we explain a preferred embodiment of the present invention with reference to the attached drawings. FIG. 1 is a cross section of a fan motor according to an embodiment of the present invention. As shown in FIG. 1, fan motor 1 of the present embodiment is an AC motor, furnished with a base portion and a bracket 2 for setting fan motor 1 in place, a rotor 4 and stator 6 disposed over bracket 2, a cover portion 8 surrounding rotor 4 and stator 6, and a fan member 10 disposed to cover the top portion and surrounding area of cover portion 8. Note that in the present embodiment the top of FIG. 1 is the top of fan motor 1, and the bottom of FIG. 1 is the bottom of fan motor 1. In addition, the surround body of the present invention is furnished with a bracket 2 and cover portion 8.

Bracket 2 comprises a bottom surface portion 12 formed in a disk shape, and a cylindrical portion 14 disposed vertically with respect to bottom surface portion 12, at the center portion of bottom surface portion 12. Annular projection 16 is formed on the outer perimeter side of bottom surface portion 12. The bottom portion of cylindrical portion 14 is a circular opening portion 14A.

Rotor 4 is furnished with an inverted bowl-shaped rotor case 18, a core plate laminated body 20 disposed on the inside wall of rotor case 18, and a rotary shaft 22.

Rotor case 18 is formed in a closed bottom cylindrical shape in which the top surface of the cylindrical side wall is capped by a disk-shaped member; the center portion thereof is affixed to rotary shaft 22 via a bushing 24. A circular indentation 26 is formed around bushing 24 at the center portion of the disk-shaped member on rotor case 18; the outer circumferential wall 26A of indentation 26 extends cylindrically around rotary shaft 22, parallel to rotary shaft 22. Note that a rotor case 18 indentation 26 does not necessarily have to be formed.

Core plate laminated body 20 is formed by laminating multiple annular core plates made of silicon steel plate or the like; short circuit rings, not shown, are disposed at the top and bottom surfaces thereof. The core plate laminated body 20 is disposed on the outside of stator 6, parallel to the outer surface of stator 6 and at a predetermined gap from the outside surface thereof.

Rotary shaft 22 is disposed inside cylindrical portion 14 at the center of bottom surface portion 12, and a stator-side bearing 28 is placed between the inside surface of stator 6 cylindrical portion 14 and the outside surface of rotary shaft 22. Rotary shaft 22 is rotatably supported relative to stator 6 by this stator-side bearing 28. Stator-side bearing 28 is affixed within cylindrical portion 14 by seal 14B, which plugs opening portion 14A on bracket 2. The top end portion of rotary shaft 22 penetrates cover portion 8 and projects outside cover portion 8.

Stator 6 is furnished with a core plate laminated body 30 and a coil 32 wound around core plate laminated body 30.

Core plate laminated body 30 is formed by laminating multiple core plates made of silicon steel plate or the like on a bobbin case made of insulating plastic. Core 32 is continuously wound around core plate laminated body 30.

The inner circumference of stator 6 is affixed to the outer circumference of cylindrical portion 14 on bracket 2. Here, the inner circumferential surface of stator 6 is positioned radially further outward than the outer circumferential wall 26A of indentation 26 on rotor case 18. Therefore even if stator 6 bobbin case 6A projects further up than the bottom surface of rotor case 18 indentation 26 as shown, for example, in FIG. 1, stator 6 does not interfere with rotor case 18. Hence the space above indentation 26 inside rotor case 18 can be effectively utilized.

Cover portion 8 is given an inverted bowl shape in which cylindrical side wall 34 and top surface 36 covering the top of side wall 34 are integrally formed, and annular indentation 38 is formed at the bottom end surface of side wall 34. This indentation 38 is disposed at a position corresponding to bracket 2 projection 16, and an O-ring 40 is sandwiched between this indentation 38 and projection 16, therefore the bottom end surface of cover portion 8 and the bottom surface portion 12 of bracket 2 are sealed. In addition, insertion hole 42, into which rotary shaft 22 is inserted, is formed at the center portion of top surface 36 of cover portion 8. Also, cover portion bearing 44 is provided between the inside surface of insertion hole 42 and the outside surface of rotary shaft 22. As the result of this cover portion bearing 44, rotary shaft 22 is rotatably supported relative to cover portion 8, and the gap between cover portion 8 and rotary shaft 22 is plugged. By virtue of this structure, the region surrounded by cover portion 8 and bottom surface portion 12 becomes an essentially hermetically sealed fluid-tight space 46; within this space 46 are housed a portion of rotary shaft 22, and rotor 4 and stator 6. Therefore a surround body comprised of cover portion 8 and bracket 2 surrounds the top (top surface side), circumference (outside circumference side), and bottom (bottom surface side) of rotor 4 and stator 6.

On rotary shaft 22, a coil spring 45 is inserted between the inner wheel of stator-side bearing 28 and bushing 24. The stator-side bearing 28 and bushing 24 are biased by coil spring 45 so as to mutually separate. This causes coil spring 45 to pass through the inner wheel of stator-side bearing 28 and bushing 24 and precompress the inner wheel of cover portion bearing 44 and set a position. Note that the precompression of stator-side bearing 28 and cover portion bearing 44 may also be performed by a web washer rather than a spring. A structure is also acceptable in which coil spring 45 is disposed on stator-side bearing 28 and the outer ring of cover portion bearing 44, and precompression is achieved by biasing the outer rings of these bearings 28 and 44.

A bushing 47 is provided between cover portion bearing 44 and fan member 10 to secure the distance between the two.

A cone-shaped sloped surface 48 sloping downward toward the center is formed around insertion hole 42 at the center of top surface 36 of cover portion 8; an upward projecting annular projection 50 is formed at the top end portion thereof, and downward-indented indentation 52 is formed on the outer perimeter side of projection 50. A plate-shaped flange portion 54 projecting outward from the outer circumference-side end portion of projection 50 is attached to projection 50, and this flange portion 54 covers a portion of the top of indentation 52. In addition, an annular projection 56 projecting upward at a position further out than the outer circumferential surface is formed at the outer circumferential surface bottom end portion of cover portion 8 side wall 34. Note that sloped surface 48 on the top surface of cover portion 8 does not necessarily have to be provided.

Fan member 10 is disposed to cover the outside of cover portion 8 top surface 36 (top side) and side wall 34 (circumference), and is formed in a cylindrical shape with a bottom having a disk-shaped top surface 58 and a cylindrical side wall 60 integrally formed on the outer circumference of top surface 58, forming in its entirety an inverse bowl shape. Multiple blades 62 are formed on the outer circumferential surface of side wall 60. Indentation 64, which opens downward, is formed at the bottom end edge of fan member 10, and projection 56 on cover portion 8 projects into the interior of this indentation 64. A downward projecting projection 66 is formed on the bottom surface of the top surface 36 of fan member 10. Projection 66 is positioned further out than cover portion 8 flange portion 54, and projects into indentation 52.

The gap between fan member 10 and cover portion 8 is thus formed into a maze shape by the structure of projection 50, flange portion 54, indentation 52, and projection 66, making it difficult for liquid drops or dust, etc. to intrude into said gap. The gap between fan member 10 and cover portion 8 is also formed into a maze by the fan member 10 indentation 64 and the cover portion 8 projection 56, and intrusion of liquid drops or dust, etc. from said gap into the space between fan member 10 and cover portion 8 is prevented. An indentation 68 is formed at the center portion of top surface 36, and in this indentation 68 fan member 10 is affixed to the top end portion of rotary shaft 22.

In a fan motor 1 having the type of structure described above, sourcing current to coil 32 so as to rotate rotor 4 causes rotary shaft 22 to rotate together with rotor 4, such that fan member 10 rotates.

Using the present invention thus constituted, the following superior effects are achieved.

A cover portion bearing 44 is erected between cover portion 8 and rotary shaft 22, with rotary shaft 22 being rotatably supported by this cover portion bearing 44, therefore gaps can be prevented from forming between cover portion 8 and rotary shaft 22. In the conventional structure shown in FIG. 2, rotary shaft 100 is supported by bearing 118 at two locations at the bottom of bushing 116, which affixes rotor 102 to rotary shaft 100. In this type of conventional structure, a gap 112 occurs between surround body 106 and rotary shaft 100. In the present embodiment, in contrast, cover portion bearing 44, which supports rotary shaft 22, is used on the outside of rotor 4 to fill in the gap between cover portion 8 and rotary shaft 22, therefore stator 6 and rotor 4 can be surrounded in a liquid sealed manner by the surround body constituted by cover portion 8 and bracket 2, and intrusion of liquid drops, dust, or the like from the gap between cover portion 8 and rotary shaft 22 can be reliably prevented.

What is known as an “outer rotor” structure is disposed outside rotor 4 and stator 6; cover portion bearing 44 is disposed above bushing 24, and stator-side bearing 28 is disposed below bushing 24, therefore rotary shaft 22 can be supported on both sides, sandwiching rotor 4. As a result, the rotor 4 support structure, which includes rotary shaft 22, is strong, and the rotary operation of rotor 4 is can be stabilized.

The present invention is not limited to the embodiment above; for example the above-described embodiment was an “outer rotor” structure in which the rotor is disposed outside the stator, but without such limitation an “inner rotor” structure may also be adopted, in which the stator is disposed outside the rotor.

For the fan motor, a DC motor may also be adopted, without limitation to an AC motor of the type used in the above-described embodiment. When utilizing a DC motor, a magnet may be used as the rotor; for the stator, a laminated core of the type described above may be used, as can other structures, such as a powder magnetic core in which powder is pressure formed, or a coreless type, in which a hollow core coil is attached to a substrate without using a core.

As a method for insulating the stator, in addition to using a bobbin case as in the above-described embodiment, insulating properties may also be obtained by powder coating a base piece with insulating resin.

EXPLANATION OF REFERENCE NUMERALS

-   1: fan motor -   2: bracket -   4: rotor -   6: stator -   8: cover portion -   10: fan member -   22: rotary shaft -   28: stator-side bearing -   42: insertion hole 

1. A fan motor comprising: a stator; a rotor having a rotary shaft; a surround body surrounding the entirety of the stator and the rotor in a liquid-tight manner except for the top end portion of the rotary shaft; and a fan member affixed to the top end portion of the rotary shaft; wherein an insertion hole is formed on the surround body in order to insert the top end portion of the rotary shaft and cause it to project on the outside of the surround body, and wherein a surround body-side bearing is provided between the insertion hole and the rotary shaft.
 2. The fan motor of claim 1 wherein the rotor is disposed outside the stator, a stator-side bearing is provided between the stator and the rotor, and the rotor is affixed to the rotary shaft between the surround body-side bearing and the stator-side bearing. 